Configuring and Backing Up Oracle Databases Using RMAN - OCP: Oracle Database 12c Administrator Certified Professional - page 152

FiGURe 3.4 The block-change tracking file

Unchanged
Blocks

Changed
Blocks

RMAN

Step 1
Query block-
change tracking
file to determine
change blocks.

Step 2
Back up only the
changed blocks
and skip the
unchanged
blocks.

Block Change
Tracking File

Datafile

To create the block-tracking file, use the ALTER DATABASE ENABLE BLOCK CHANGE TRACKING
command. By default, Oracle will create the block-change tracking file in the location defined
by the DB_CREATE_FILE_DEST parameter. If that parameter is not set, Oracle will require that
you provide a destination and filename for the block-change tracking file. Here is an example
of the creation of a block-change tracking file:

SQL> alter database enable block change tracking using file
'c:\oracle\block_change_tracking\orcl_block_change.fil';

You can find the location of the current block-change tracking file by looking at the
FILENAME column of the V$BLOCK_CHANGE_TRACKING view. You can use the STATUS column
of the V$BLOCK_CHANGE_TRACKING view to determine if block-change tracking is enabled.

You should perform a level 0 incremental backup after creating the block-
change tracking file. This is because the parent level-0 backup bitmap must
be in the block-change tracking file.

Types of Incremental Backups
Two types of incremental backups are available for you to choose from:
■ Level-0 incremental backup
■ Level-1 incremental backup
The level-0 backup is like a full backup (sometimes it's called a base backup), except that
incremental backups can be based on it (they cannot be based on a regular full backup).